15 



resemblance to Man. In the same degree they impress that anthropic 

 feature upon the face of the living Gorilla. In some pig-faced 

 baboons there are ridges and prominences in the naso-facial part of 

 the skull, but they do not really affect the question as between the 

 Gorilla and Chimpanzee. All naturalists know that the Semno- 

 pitheques of Borneo have long noses, but the proboscidiform append- 

 age which gives so ludicrous a mask to those monkeys is unaccom- 

 panied by any such modification of the nose-bones as gives the true 

 anthropoid character to the human skull, and to which only the Go- 

 rilla, in the ape tribe, makes any approximation. 



No Orang, Chimpanzee, or Gibbon shows any rudiment of mas- 

 toid processes ; but they are present in the Gorilla, smaller indeed 

 than in Man, but unmistakeable ; they are, as in Man, cellular, 

 pneumatic, and with a thin outer plate of bone. This fact led the 

 author, in a former memoir, to express, when, in respect to the Go- 

 rilla, only the skull had reached him, the following inference, viz. : 

 " from the nearer approach which the Gorilla makes to Man in com- 

 parison with the Chimpanzee or Orang, in regard to the mastoid 

 processes, that it assumed more nearly and more habitually the 

 upright attitude than those inferior anthropoid apes do." * This 

 inference has been fully borne out by the rest of the skeleton of the 

 Gorilla, subsequently acquired. 



In the Chimpanzee, as in the Orangs, Gibbons, and inferior 

 Simice, the lower surface of the long tympanic or auditory process is 

 more or less flat and smooth, developing in the Chimpanzee only a 

 slight tubercle, anterior to the stylohyal pit. In the Gorilla the 

 auditory process is more or less convex below, and developes a ridge, 

 answering to the vaginal process, on the outer side of the carotid 

 canal. The processes posterior and internal to the glenoid articular 

 surface are better developed, especially the internal one, in the 

 Gorilla than in the Chimpanzee ; the ridge which extends from the 

 ectopterygoid along the inner border of the foramen ovale, terminates 

 in the Gorilla by an angle or process answering to that called " sty- 

 liform " or "spinous" in Man, but of which there is no trace in the 

 Chimpanzee, Orang, or Gibbon. 



The orbits have a full oval form in the Orang ; they are almost 

 circular in the Chimpanzee and Siamang, more nearly circular, and 

 with a more prominent rim in the smaller Gibbons ; in the Gorilla 

 alone do they present the form which used to be deemed peculiar to 

 man. There is not much physiological significance in some of the 

 latter characters, but on that very account, the author deemed them 

 more instructive and guiding in the actual comparison. The occi- 

 pital foramen is nearer the back part of the cranium, and its plane 

 is more sloping, less horizontal in the Siamang than in the Chim- 

 panzee and Gorilla. Considering the less relative prominence of the 

 fore-part of the jaws in the Siamang, as compared with the Chim- 

 panzee, the occipital character of that Gibbon and of other species of 

 Hylobates marks well their inferior position in the quadrumanous 

 scale. 



* Transactions of the Zoological Society, vol. iii. p. 409. 



